1. Field of the Invention
The present invention relates to drive circuits of computer systems, and particularly to a drive circuit which can drive a mode indicator to show a working and a sleeping status of the computer system.
2. General Background
Conventionally, to save power sources, a sleeping mode is used in a computer system. Accordingly, an indicator is arranged in each of a PCB and a monitor, to show a working status or a sleeping status of the computer and the monitor. CN. Pat. No. 03236782.1 discloses a circuit controlled by a single chip to drive an indicator. The single chip uses a program to control the circuit. The indicator light is steadily on to show a working status. The indicator light flickers to show a sleeping status.
However, a drive circuit of the indicator must be controlled by the single chip. It is unduly complex to use the single chip because a controlling program is required. In addition, it is costly to use the single chip to control the indicator. Furthermore, the single chip not suitable for controlling more than one indicator, which may be required in some computer systems.
What is needed is a drive circuit which can overcome the above-mentioned shortcomings.